Emerald Ash Borer
What is Emerald Ash Borer?
Emerald Ash Borer is a green beetle that affects only ash trees. When EAB larvae feed, their galleries injure the phloem and xylem that make up the plant’s circulatory system. This interferes with the tree’s ability to transport nutrients and water. When the circulatory system is compromised, the result is death. The larvae also affect the tree’s ability to transport insecticides, which is why it is critical to detect EAB before too much damage has occurred. If 50% of the canopy has experienced decline, studies show that it is probably too late to treat for EAB. So how do you identify EAB?
The typical homeowner can use these three symptoms to identify EAB.
1. The trunk will have d-shaped exit holes when the adult beetles leave the tree.
2. Visual fissures on the bark are the result of callous tissue formation. Pulling the bark away reveals serpentine galleries of the boring insect.
3. The top third of the canopy will decline in both leaf size and density. The tree will look significantly thinner on the top.
So what about Dane County?
EAB was detected in Madison in 2014, and has since spread across all of Dane County, as well as most of the state. Most trees which had not previously been treated, are either already infested, or are close to infested trees and vulnerable to attack. Those trees which have not been attacked yet, or have only a one year infestation, can still be saved using a trunk injected insecticide. Trees with more than a one year infestation, are not likely to survive, even with a high dosage of insecticide. In this case, removal of the tree is the best option.